Pigments that are generally superior to dyes in the points of light fastness, water resistance and ozone resistance are widely used as colorants in inks for ink-jet recording. When ink-jet recording is carried out with a pigment series ink set, the dispersion stability of pigment particles may be improved to realize high ejection stability. Steps also have been taken to restrain feathering (in particular, feathering at the recorded part with a black ink) and bleeding (in particular, bleeding between the recorded part with a black ink and the recorded part with a yellow ink), and to improve color developing properties and transparency of color inks.
An ink set for ink-jet recording has been developed in which the relative size of the particle size between the pigment particles of a black ink and the pigment particles of color inks is adjusted. However, ink-jet recorded materials having good printing quality may not necessarily be obtained by mere adjustment of the relative size of the particle size between the pigment particles of a black ink and the pigment particles of color inks. Specifically, feathering and bleeding on the surface of plain paper may not be sufficiently restrained. Further, when pigment particles of color inks are large, second colors such as red, green, blue, and the like may appear dark and dull when applied to glossy paper. Unevenness in solid parts may also result. In addition, in connection with the OD (optical density) value of a black color on plain paper, a problem arises in covering power and the OD value lowers when particle size is small.